Proven clearances for stageII


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May 25, 2001
Would someone like to share what bearing clearances,need to be on a stageII.
Reading the Buick Power Source book is good,and there specs are well proven.
Have read lately,that all out drag race motors should have slightly "looser" clearances,just to be sure there is enough oil around the bearing.???
This motor has seen 7500rpm,but thats not normal I hope.
Stage clearances

Austin, the 7500 is COMMON for these engines!!;) we are running a NA stage 2 odd fire and leave the line at 7500 and shift at close to 8000.
As for the clearances. The "book clearances" are good to go.
Those dimensions are, for the most part, setup for extended run times at 7500-8000 and are fine for short blasts in a drag car. BE SURE you have sufficient pressure when doing it. The stock car and road race guys have dry sumps and run pressures, under load, in the 80-90psi range. My dutt system runs 80psi thru the traps at 6200. Brgs look like new after a season on them.[setup to Busch specs]

What kind of oil weights are being used with what clearances also ?

Paul Thompson
Lets say this is a wet sump motor.
Clearances and oil weights,I too would like to know this

PRessures and clearances

My system is the Dutt. external pump w/ a remote filter and cooler.
My engine is a ASA shortblk assy, running the brgs that were in the engine when I got it!! [They are coated Clevites and looked so GOOD, and were exactly at the clearances I wanted, I reused them!!] w/ the exception of the cam brgs. These are CLEVITE #1360.
The brgs are at .0025" on both the rods and mains. Crank end play is .004"
I have the DUTT external relief turned DOWN to 80psi, hot, at road speeds and 20 psi at idle.
The engine was a dry sump engine when I got it. I see NO difference w/ the DUTT system as far as the ability to run "dry sump" clearances w/ a wet sump setup.;)

This setup works SO WELL, that the oil press. ga. acts EXACTLY like a tach as it responds to throttle exactly as the tach does.!!:D
And to top it off, the ga. is electric.

I just checked the brgs after some fuel system and head problems and about 50 1/4 passes in the low 10's at over 130. They look exactly as they did the day they were put in!! :)

As for the odd fire engine in the COBRA, it too is setup w/ the ASA/Busch clearances. However, it does use the dry sump,and is consistently turned to over 8000 w/ leaves over 7000:eek:

Geez Chuck, If I'd have known those engines were that good I would have charged more for them. Any way, I run a straight .0025 on my dry sump engines. When I was running wet sumps I did close the rods up to .002. My engines are NA and I turn them consistently 8200 to 8400. I've used Valvoline 20-50 racing oil for about ten years and have never had a oil related problem. When one explodes its usually caused by a rod bolt or broken rod.
Well the difference is that on a dry sump, the pump pumps WAY MORE volume than the Dut. system is capable of pumping, it is a big difference. You set the clearances loose on a race engine in order supply a greater oil wedge to act as a cooling medium as well as a greater cushion. With a dry sump, you dont have to worry about running 20 psi at idle, 80 at full song etc etc. With the system operating at it's peak, oil pressure MAY vary 15 psi hot,cold, idle, or 10,000 rpm.
A dry sump is WAY more reliable and produces more horsepower than a wet sump. The Dut. system is an excellent choice for converting a dry sump engine into a wet sump as it takes alot of the hassle out of the equation
On a wet sump, I wouldnt run any looser than .0025 on the mains and .0022 on the rods, if you put a dry sump on it , loosen both up to about .003. I like to use Valvoline Racing straight 40 weight. Just my opinions but these clearances have worked for me on wet and dry sump engines producing in excess of 1200 hp at 8,000 plus RPM's
Bill Anderson